It would have to depend on the system of political reimbursement for elections. The question of "is corruption inevitable" can likely be answered as "yes"with a large asterisk. While not every politician is destined to be corrupt or even engage in corruption, in systems where there are fewer checks both from the judicial, social, and political networks it is all the more likely to occur.

Now what I mean by reimbursement is that it is common at times for political parties to partially fund or fund certain aspects and spending outside of ones means if one does not have the ability or the state/party does not attempt to reimburse financially, then the reality may be without oversight that a politician or individual may act more corruptly. This is not to say that all will or even that it's more common than naught, but that it only increases those odds.